[Wannier] occupation of Wannier function

[Arash Mostofi]

Hello there,

Adding to Ivo's reply:

Without disentanglement the occupation numbers are always 1 (or 2 in the 
case of spin degeneracy). With disentanglement, and just considering the 
Gamma-point of the BZ for simplicity, the occupation "number" becomes an 
occupation matrix f_{ij}. See, for example, the discussion leading up to 
Eq (9) for f_{ij} in

Andrinopoulos et al, J Chem Phys 135, 154105 (2011);
http://link.aip.org/link/doi/10.1063/1.3647912

Computing f_{ij} is not implemented in v1.2 of Wannier90, but will be in 
the next release. It is fairly straightforward to code and would look 
something like this:

! aam: calculate V = U_opt . U
do s=1,num_wann
  do k=1,ndim
   do m=1,num_wann
     v_matrix(k,s) = v_matrix(k,s) + u_matrix_opt(k,m,1)*u_matrix(m,s,1)
   enddo
  enddo
enddo

! aam: calculate f = V^dagger . V
do r=1,num_wann
  do s=1,num_wann
   do k=1,ndim
     f_w(r,s) = f_w(r,s) + v_matrix(k,s) * conjg(v_matrix(k,r))
   enddo
  enddo
enddo

Best wishes,

Arash

--
Dr Arash A Mostofi
Departments of Materials and Physics
Deputy Director, CDT on Theory and Simulation of Materials
Imperial College London, London SW7 2AZ, UK
+44 (0)207 594 8154 | www.cmth.ph.ic.ac.uk/people/a.mostofi

On 03/04/2013 14:09, 昱璋陳 wrote:
> Hi guys!
>
> I have a question about Wannier function.
>
> Can we get the occupation number of wannier function through this
> Wannier90 code?
>
> thanks!
>
>
>
>
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